As far as the AEP's go, the TM is better internally and externally. Externally, the plastics are much higher quality, the slide fits a lot better, and the sights aren't quite as cheesy looking. Plus full trades, if that matters to you. Internally the TM is simply more consistently made. The Cyma 030's are terribly inconsistent from gun to gun. Some shoot fantastic (as good or a bit better than the TM) and some shoot horrible. Unfortunate there's no real way to know which you are going to end up with before hand.
That said, the TM is well over twice the price. If price is no object, go for the TM if for no other reason than the trademarks and nicer quality frame. If you are on a budget, get the Cyma. Regardless which gun you get, only buy TM mags. The Cyma mags suck balls. As far as G18 vs M93R if you can afford the TM it's a matter of preference between the two. Performance wise they are identical. If you can't afford the TM go with the Glock because the M93R clone leaves a lot to be desired.
I love my AEP's. I'm up to 13 of them now. That said, there's some things you have to be aware of before getting into them.
1) Parts. AEP parts are relatively hard to come buy and expensive. Stateside your only option for them is Airsoft Atlanta. Overseas EhobbyAsia and WGC carry the largest selections. Parts are frequently out of stock however.
2) Performance. FPS wise, you aren't going to get them over 330fps. You'll be lucky to get them to 300fps. Personally, I don't have an issue with this. You just have to be aware of your limitations. Range varies wildly, especially with the Cyma's. Some seem to struggle to make it 75 feet. Others will inexplicably float BB's out to 200ft. Admittedly the BB's going so slow you can duck out of the way at that point but it's still astonishing. That said, the relatively lower performance can be offset with stealth. The guns are pretty quiet to begin with and can be made basically inaudible from more than 5 feet. I've yet to wield one at Vanguard without at least one person commenting that he couldn't even hear me shooting.
3) Batteries. The standard AEP batteries are low discharge and will not last you a full game unless you never use the gun. Converting the gun to use LiPo's makes you feel like you have a whole new gun. Improved rate of fire, trigger response, and battery life all from a (relatively) basic upgrade. Converting the gun to use LiPo's is going to run you around $50 in parts (not counting a LiPo charger if you don't have one) and will require soldering. Some people don't want to get that involved in it in which case you are stuck with the stock batteries.