Have used Three for the past 5 years (3 in Wrexham, N Wales, mostly from home for data - 15 GB/month) but more recently during 2012 on mobile with 600 minutes and 3000 texts, unlimited data...
I switched to T-Mobile in February but EE are "removing duplication" of Orange/T-Mob masts and for the past 2 months I've had rotten signals ('Emergency calls only' 'Not registered on Network' calls dropping part way, streaming radio {nothing fancy, just BBC R4} dropping every 10 minutes) so have taken out a fresh 2 year contract with Three.
I got a refurbished BlackBerry Curve 9320 (because I already have other mobiles I can use for Three) and that was the cheapest deal (100 minutes, 5000 texts, unlimited data, for 13 pounds/month) I could get.
I was after the unlimited data, rather than talk time. However, if you are after an Android mobile I think it would be good to mention what you've seen and at what price before you choose a deal and then find it has limits...
For example, I've used the Samsung Galaxy Ace, Europa and Mini, and while they are 'adequate' for a few apps, I would be happy to suggest getting a much newer Sony Xperia Tipo (60-80 quid on PAYG at T-Mobile or O2) and getting it UNLOCKED, then using it with a SIM ONLY deal from Three (or getting that Blackberry deal, and using the SIM in the Sony Tipo).
Why the Sony Tipo ? It's running Android v4 (not 2.2 or 2.3) and it has bags more memory for storing Apps, so won't give constant "low storage" warnings like the Samsung Europa or Ace.
Later Samsung models like the Ace 2 would probably be fine, but I don't know what sort of budget you have and whether you are being pestered for a Blackberry or Android :)
The refurb model I went for was on *> www.three-clearance.co.uk