Depends massively on personal preference really. Out of everything I've owned/fired then it has to be my GBB Vz61 Skorpion from KWA/KSC. Shoots around 290-300 fps on green gas, is as compact as a regular pistol, laser accurate once the hop has been dialed in correctly and is very sturdy. Also it's rarely seen at most skirmish sites (most people opt for the AEP models) so you've got that added "uniqueness" factor. Downsides though are the lack of aftermarket parts, mags aren't cheap and neither is green gas itself (unless you buy propane to power it).
For electric guns then I'd say the ICS MP5 is a pretty good bet out of the box. Compact, decent trigger response and can hold it's own in woodland if you need it to. Again this is just from guns I've owned or fired personally.