Reading these forums I still see there is a misconception about the meaning of "progression" or "advancement". What we`re really talking about here is a "sidestep".
When talking about careers & airline flying we`ve basically got 3 categories or industries, i.e
Regional / Short haul - Glass cockpit heavy Turboprops (ATR, DHC8),
Short Haul / Medium Haul - Regional / Medium sized turbofans (Emb/737/A320)
Long Haul - Heavy turbofans (747, A330)
The differences in actually flying between these categories are fairly small, it`s really only the operations that might change to some extent. They`re all pretty much fully automated these days, I still hear pilots mentioning "stick and rudder" skills on nextgen turboprops, another misconception. Those of us who have flown in multiple categories know that it`s all the same s**t.
Each category is potentially a career in itself, progression or advancement would be F/O, Capt, TRI / TRE, post holder for example. There are pros and cons to each category, I personally prefer the regional TP as the advantages really do outweigh the other categories but what the OP is talking about here is boredom which most of us suffer after a while flying any aircraft. This often means pilots want to make a sidestep to another category to try something different which can be difficult due to hiring policies. As mentioned previously long haul and medium turbofan pilots can find it just as difficult to sidestep into the TP industry so it works both ways. Every now and then doors open up between the categories due to supply and demand but often it means starting from the bottom again and joining cadets.
With the introduction of LCC`s and cadet schemes, the 737 and A320 have now become the main entry level aircraft for new pilots although some long haul operators take on cadets also. So for the OP, I would advise remaining in the TP category as you are potentially in a better position than starting at the bottom again. Changing to a better type or operator within the same category would be "advancing". I constantly see pilots making that sidestep and trying to run back after realising.
Of course there are exceptions to the above with regards to hiring policies, direct entry captains positions, airlines operating within multiple categories etc.
Of course there are a number of factors when considering a move within your category or making a sidestep but it boils down to the individual operator (RATE of pay, base, home every night etc).