I've kept both Jacksons and Veileds; Jacksons are my favorite….but i do not consider them a starter cham. Montane species require extra care, vs Veileds that are more tolerant of not only wide temperature ranges, but supplementation; montanes have slower metabolisms are very sensitive to supplementation.
My first few chams were Jacksons 20 years ago and i could never get one to live longer than a year. I gave up and kept Veileds until recently, as i perfected my cham keeping techniques and the Veileds live 5-7 years. My current Jacksons is two years old, and the key is correct supplementation, natural UV exposure whenever the weather permits, cool temps…and lots of water!
I highly recommend a veilded for a first cham. They're the cheapest and easiest of the 3 commonly kept species.