I suppose that all depends on your mission requirements. If you are talking about the EC145 (you wrote 145) than you are looking at a quite different aircraft (larger cabin space, rear-clamshell doors, more seats,etc.)
The A109 is certainly a great performer, the K2 and in particular the Power. never the less, it only seats five (1+4) and if, for example, you were to use it for medevac operations, the access, internal space requirements etc, are certainly more limiting as compared to the EC145 /BK117.
I hope that this answers some questions, if you were to talk about this coparision. Remember, it is important to keep in mind what operation you are going to use it for.
I have flown helicopters in Oman before and believe that either of the aircraft would have sufficicent performance for most operations.