I'd tend to go the opposite direction of Nikonmike - I like the larger sensor and less reach of that choice. But I guess it much depends on just how far off the wildlife you often shoot will be. In Florida, we can sometimes get pretty close - 600mm is usually enough for smaller birds in the forest, and more than enough for wading birds...what we run into much more often is challenging lighting - shady forests with heavy tree canopies, and birds often trying to avoid the sun as we're so warm down here. Plus, through much of the year it's so hot and humid here that you can't really shoot birds too far away even if you have the reach, because atmospherics will destroy the shot if the bird is more than 100 feet off.
If I were in the market for a bridge cam, I'd likely get the Sony RX10 IV. It's pricey, but seems to be the best bridge cam at covering all the bases - larger sensor to help in more challenging light, good reach up to 600mm, and actually very capable with BIF with fast OSPDAF focusing.
I shoot with a DSLR system, but also with a mirrorless system which is small enough and light enough that I haven't been tempted enough by the bridge wildlife cams. I have an original RX10 (only 200mm) for a travel cam, but it doesn't have the reach for wildlife or birding.
