I'd recommend the 3r tho ted, never used a 3s, so can't comment on that one, but went for the 3r as thought to myself that i'd otherwise just end up wanting it in the future.
I like you was running pretty cheapy plastic geared analogue servos, however on purchasing the 3r realised would need a better one, got a ko propo one for £30 and the difference is amazing
If I had more cash would upgrade my other servo too.
The 3r is fantasticly easy to programme, responsiveness and adjustability is amazing, the model memory is excellent too. All round excellent piece of kit.
Price wise the going rate for a 2nd hand 3r is around the £160 mark, which is about the same cost as a new 3s, so if you look at it that way you'll be spending the same amount of money.
The one I got off the bay came with all packaging, manuals and the bits that came with it. The gear itself was immaculate, protective plastic still on the tranny and not a mark on it
I (as you've probably guessed) do not regret buying a 2nd hand 3r over a brand new 3s.
Cheers
matt