first of all, all the exp enhancing skills are the must, if hero is planned to develop. Thus, for couple of levels nothing happens .... I personally think those should be gone, exp enhancers are too good to pass on them, on the other hand, they are totally boring ... 

second, warrior's skills are kind of boring +1 attack, +2 attack and so on for like 6-7 levels before you get sweep ... On the other hand, playing wizard: you have all this summons, new spells etc. and leveling is way more exciting ...