Problem is - every man and his dog has an opinion as to 'what am bestest' when it comes to guns for a certain budget and technical proficiency of the user. Then there's the issue of what platform (M4, MP5, AK, G36 etc).
I would be looking up the usual retailers (Patrolbase has a good range at reasonable prices), and seeing what you think looks coolest.
Come up with a sort list and post up on here if you need help/opinions.
In the mean time, I would not buy that gun you've been offered until you can see what's going on with that stock. I don't think it has been mounted properly. The buffer tube castle nut (the ring with notches cut out) should be flush with the back of the receiver:
Versus:
If you like the LR300 style stock, you can buy the Evolution LR300 rifle from Zero One Airsoft for £255 brand new:
https://www.zerooneairsoft.com/products/Evolution_AEG_LR300_ML-AXL_Black