This is just my personal view. I would go for the 450h with due diligence regarding MOT history and service record. I would NOT purchase an older 450h with air suspension. These are the SE-L or Premium specification. You would be very unlucky to get lots of trouble with a Lexus. All cars can go wrong, but with Lexus it seems that ONE thing can go wrong and IT CAN be expensive to fix but after that one issue,you rarely get a catalogue of failures. there is a member on here who suffered a catastrophic failure to his LS 430 but he still went and bought another Lexus.
Buying older cars is risky but if you buy an older Lexus you have more chance of it giving reliable service than the equivalent BMW or Mercedes. The Honda is a very good car ......... but until you have owned a Lexus ........ you will never know the difference! Owning being the operative word!
Good luck with your decision, read as much as you can on this forum.