In general, the majority of ELNs will allow you to demo the ELN for free (and even use for free as a single user, although there is a cost when implemented by the institution or lab), so my suggestion is to test a variety of these. This may be a little time-consuming, but will pay off in the end if you are transitioning to ELNs.
Several helpful resources that may help inform your decision on what ELN suites you best:
In general, they will all differ in: 1.) User-interfaces; 2.) interoperability and flexibility; and 3.) the pricing model.
In no particular order, here are some of the more popular, higher rated ELNs: