Hi Fizzy,
If you just want a general use lipo charger, you should get one off Hobbyking.com- The chargers are quite cheap and tend to work quite well and are quite easy to use. You mentioned that you wanted AC, which is a good choice because you dont have to go and find a suitable power supply.
Two chargers looked appropriate from the AC chargers section.
1: Imax B6-AC
2: Hobbyking B6 AC/DC
The Imax is very popular would be a better charger as it can monitor voltage and cycle batteries. However the Hobbyking charger would be an easy way to just plug in and charge your batteries. They both charge at 5 amps max so you can charge most batteries quite fast. If you are setting the current set it at the same amount of amps as your battery has, for example: a 2000mah receiver pack would be charged at 2.0 amps and a 4000mah rc car pack would be charged at 4.0 amps. Some say you can charge batteries at a faster rate than this but to prolong the life of your battery I would stick to this rule.
I would also get an Imax multi plug adaptor box so you can easily plug in most batteries even if they have different connectors. Also get a Hobbyking Cell checker with low voltage alarm so you can easily check the voltage of your packs.
Good luck,
Aston177