Always are (only joking)
Very helpful stuff that no one can do without though =p
EDIT: And to add to it, for a side-arm, it also depends on style, but for this category, I as a personal recommendation would say the TM hi-capa 5.1 far and beyond anything else your thinking of, because it is the most customizable GBB on the market by a long shot, with any and every style you want (ask Illusion), it performs very well with just minor upgrades (hop-up rubber, new nozzle and inner barrel). And it of course comes with the TM bullet-proof reliability. If you leave it stock, it will still perform admirably. TM have really outdone themselves with the look of the plastic, it looks extremely good, and better than some metal guns I've handled. They usually run for around 300-350. Mine came nearly BNIB for 300.
EDIT EDIT: Just because a pistol is full metal doesn't mean it's good, cheapo pot metal (low grade iron, 100 grade steel, ect ect.) some times turn out worse than good quality plastic.
Holy crap EDIT: BTW: New TM M4/M16s don't have barrel wobble anymore. Since your looking for "decent" accuracy, I would recommend the CA RIS M4, it has great, rock solid externals, and what you can kind of consider as "pre-upgraded" internals... They are much more solid and technically will take a lot more punishment than TM internals, although some people on here have run their TMs with upgraded springs and metal bushings, and have gotten no problems. An M4 RIS will allow for a retractable stock, and a PEQ battery box on the front for large batteries(upsets the balance of the gun, but you can argue it's closer to real steel); and any other trinkets you can think of(don't be an accessories whore). The M4 has a very respectable 363mm inner barrel length, allowing for a decent amount of accuracy. It is also the gun with the most aftermarket parts avalible, despite the V2 mechbox being the weakest out there. Did I mention the very brand new CAs have fully functional bolt catches now?