Stay away form the Sig552. They are difficult to upgrade have the least 3rd party upgrades of any TM (Outside of the Type89 which pretty much ships upgraded). Your stuck using a mini battery unless you go external. Unless you are totally sold on it by the looks alone.
CA SLR105 seems fine. Haven't seen/heard of any being returned due to reliabilty probs. But really, any decent AK is worth it. (TM, G&G, VFC)