At which experience levels does the game seem most enjoyable?

The game feels very different when your playing at low or high experience point levels. I guess they can be referred to as low, medium, high and very high.

1.What levels do you enjoy most playing at and why?

2. If a new game was to be designed with the BG engine with the BGEE modifications, would you want it to start at level 1 or carry on beyond the levels that will be reached in BG2EE?