First, trot over to the USAK forum. Click on Search this forum. Enter the words "casual semi trad" in any permutation. You should find some useful discussions, as this comes up often!

Short answer: there's no wrong answer, you can't lose with either. The casual is (surprise!) more "casual." Having said that, I incline just perceptibly to the semi-trad (2 in hand & one on order) but I love my one casual.

OK suggestion: Instead of 2 casuals, buy one. Then (1) you can decide for yourself, (2) if you decide on another semi-trad, your kilt fund is already halfway there.

See especially: How hard do you have to look to tell a trad from a semi-trad?
On the fence between casual or semi-trad