As many others we also used SES for a long time, and we were quite happy with it.
But we decided to test some other solutions just to be aware of what is there on the market. We requested trial version from LMKR, LR Senergy,
HSI, Geonaft, ROGII etc. I didn't have much time for the tests and I may be a bit superficial here, but most of all I liked Geonaft software from Geosteering Technologies Inc.
Geonaft is way more user friendly and nice looking than any other soft (Competing I guess only with Star Steer here). And, which is more important, it is more robust and more functional. It works well even on weak machines (Win 7, 2gb). You can choose which module you need for each specific project and pay only for it. I discussed it with my team and we decided that starting 2016 we are switching to Geonaft.
Please note that it is my personal opinion based on my experience and you may find some other soft more convenient.
Anyway, before making your final decision I suggest that you try 4-5 different providers and choose which you like the most. Pricing is relatively the same everywhere.