The best option for what?
I've lost track of what your budget was, but comparing with the prices of the bridges you talk of....
A Panasonic G3 with 14-42 (Or the older 14-45) lens can be found on ebay for 80-140 or a G5 which has several advantages for slightly more most days of the week and a 45-150 lens for £100-140.
The 45-150 lens is very useful and inexpensive, it can be updated to give dual OIS when used with the later Panasonic cameras that supports Dual OIS, and used with a screw on close up lens, gives very good close ups of bees, butterflies and flowers etc without getting too close to disturb them.
However if you want good sharp photos of flying things and the moon etc. then yes, the lens becomes pricy. But most affordable bridges do a poor job of these anyway, they look OK at a quick glance, but overall quality is sadly lacking.
If you are patient, they come along at good prices. (the cheapest I have bought on ebay was £20 for G3 and £25 for a G5, and £32 for a G3 with lens)
I personally think that you might trim the "flying things and the moon etc" from you wish list, and look for the best choice without that, as it will either be too expensive, or very disappointing.
It will also allow you to look at more choices. I suggest Panasonic M43 as I use now it (previously Pentax, then Canon APS-C), but I'm not saying it is the best or only choice.
This is why I don't think small sensor super-zooms are the best solution for distant shots that don't fill the frame
View attachment 400169
The moon was small in the frame anyway, but it doesn't look too bad until you look at the detail as per the insert.
I find this become very discouraging on many subjects, and often negates the supposed advantage of a long zoom.
If this is what you are expecting, that's fine, but if you are expecting more, small sensor super-zooms are not the answer.