JC
I have had similar problems and can totally understand where you are coming from.
How I personally look at it, is that the Capt is under a lot of pressure, and license is on the line, so they will do what is required to protect that within reason of course.
I also think to myself, that they are experienced Pilots and may see something you don't, it would be better for them to react before its too late.
I would maybe talk to the Capts concerned, and ask them why they are interfering with the controls, if you do not get a satisfactory response, I would as others have said, is approach a nice Training Capt.
Whwn you see the TC, explain at first you don't want to mention any names, but explain what is happening on your flight.
I noticed you said that you are quite experienced, so this may sound harsh, but maybe tell the TC if he wouldn't mind rostering you on some flights with TC, although on record it would not be classed as a training sector, but therefore it would give you an opportunity to discover if you any problems.
If the TC's are happy, then that just proves your case and then you can move up to the next level.
I had the same situation and it still happens with certain Capts, but speaking to other FO's they say exactly the same.
I flew with some TC's and they do not interfere or anything, and I work much better.
I had one normal line Capt, it was a strong 18kts X wind in rain, he told me that he is not going to make any inputs, he will as per SOP, cover the controls, but the rest is up to me, as he said your Command Training starts when you are in the Right Seat.
Without boasting, I did a really nice landing and got in nicely on the Centre Line, and it made me more confident and determined to do better each flight and think for myself.
I wish you the best of luck.