It all depends - some people like iPads and some like tablets and actually the iPad is a tablet it's just Apples name for their tablet (it's like saying in the 80's which was better - a Sony Walkman or a portable cassette player - they're the same thing Walkman was just the brand name for Sony's portable cassette player).
The main question though is which is better an iOS based tablet, a Windows based tablet or an Android based tablet. All three do have their pros and cons.
iOS - iOS is a very good operating system, if your used to Mac OS and have a Mac or have an iPhone and like it then this is possibly your best option. The only major problems with iOS is the various restrictions placed on it. Apple are very protective over their iOS and as such some software and hardware wont always work with iOS. Flash and Java both are not available on iPad's which can cause some issues with some websites that require this, although many websites now are moving away from Flash and moving more towards HTML5 as this is much better and compatible with many devices, including iOS, but there are still quite a number out there that are still using Flash - as for Java this is a much bigger issue as it is still a lot more popular than Flash and on some gaming sites you can find issues with the lack of Java. Also with iOS if you want to print from your tablet you'll need to get a specific Airprint compatible printer, some none airprint printers will still work with the use of third party apps, but many are restricted on what you can and can't print and can be quite tricky to get working properly (I've found Canon's printers are really tricky to get working on iOS). Also with iOS your stuck with just one brand - all iPads are made by Apple and they're are different versions out there but that one version always has the same things on them and if you want something a bit different like a higher resolution camera or more internal memory your pretty much restricted to what Apple offer.
Android tablet - Android tablets are good, they come in a variety of different flavours - multiple companies make Android tablets so unlike iOS your not restricted to those made by Google/Motorola (although some of the Google ones are actually very good). If you have an android based mobile phone and are used to it then it shouldn't take too much to get used to an Android tablet. An android based mobile phone is pretty much any smart phone that isn't a Nokia, Microsoft or Apple (although HTC do also do a few Windows phones too). The handy thing with the fact that multiple companies make Android tablets is that it allows for so much more diversity. You can get pretty much any tablet that will do specifically what you want to do with it - they range from basic tablets with just a browser and wi-fi all the way up to all singing all dancing full HD screens, UHD cameras, loads of memory, etc. There are also various editions of Android - there is Android v1.x-5.x, 5.x (Lollipop) is the latest edition, but many devices are still using some version of 4.x Android tablets do have a massive advantage that they link very easily to your Google account, so if you have GMail, using Google Photos, Google Contacts, Google Drive, etc all of these can be transferred across your various Google accounts when you login - so you'll find if you've got an android based phone and you login on an android based tablet that all your contacts should automatically copy from one device to the other, and the same with pictures that have been backed up. Google are a lot more open than Apple when it comes to developers. This does have some advantages and disadvantages - one major advantage is that many of the android tablets do have a mobile version of Flash (although this is being phased out more and more now, and the Flash is an older version - but it's actually only a matter of time before Flash is totally killed off), and also they do have versions of Java, so it can be easier to get things running on here, but of course that also does have it's disadvantages - there is a lot of stuff in the Play store, including junk that hasn't been properly checked by Google, so you've just got to be careful with what you install. As for other hardware, the main hardware for people is getting printers working. Google tablets tend to use Google Print for printing facilities, and if you've got some kind of network printer you can usually find that Google print works fine with those. It's certainly nowhere near as restrictive as Apple print.
And finally we get onto the Windows tablets - pro's to owning one - if your used to Windows 8 and you like Windows 8 then well that's a good thing. The Windows tablets can be picked up for a lot less with a lot more features on than either the iPad's or Android tablets, although some basic Android tablets can be cheaper but have less functionality. Even though these are Windows based tablets it doesn't necessarily mean that all your Windows programs will run on it. These tablets use the ARM range of processors where as most Windows programs are wrote for 80x86 series processors, therefore the developers need to recreate the software for the ARM CPU). If you have a Windows based phone and like it - like the Nokia Lumia range or Microsoft phones then you might get on with this tablet. The Windows based tablets though can be a bit complicated to use, and as they were very late to the tablet table they are considered quite far behind the times, and certainly don't have anywhere near as much support from communities as either the iOS or Android tablets.
Out of the three - if it was my choice it would be the Android tablet as it has all the functionality, support and is much more open than the Apple device, also the different brands allow for a lot of different choice rather than being stuck with what ever Apple offer.