No real reason not to get a bullpup as your first, although there's not as many good bullpups as regular AR's but still a decent selection.
They often do have some compromises to get used to though.
Type 98b by realsword is a fantastic gun but the battery setup is tricky to say the least.
F2000 is generally all round good but the trigger system has some slight issues.
TAR-21 (ares, not the sportline) has great external quality but the internals are....ares and so a bit shit.
There's several decent L85's out there.
TM and G&G P90's are very solid if you don't mind the tiny ergonomics.
Plenty of AUG's out there, they generally don't have fire selectors though, so two stage triggers limit where you can use it somewhat.
There's also the APS UAR, cheap and fairly well made. As long as you don't mind the fact there's no real steel version.