The most appealing and upgrading rentals are typically the most popular and lucrative.

Rentals in PC are popular, whether short or long term.

Claremont CA 91711 (check on Zillow if you like to see purchase etc ) (We are finishing the landscaping, driveway and ADU together)  ADUs are super popular near downtown columbus ohio as well with a council variance. did you do all the zoning and plans yourself or hire an architect or attorney?

Like Bjorn said, there are a lot of overpriced properties currently so value add projects have been more popular in the current market as you can get in much cheaper and create value. 

For example the city of Frisco is a pretty popular place to live today, population over 200,000, and I'll bet there are less than 100 duplexes.   

Like a lot of things real estate over the last few years, there are a lot of people that leaped in without any real knowledge or plan, and they are not doing well.You are also right that a well located property with all the required work needed to differentiate yourself will yield a solid return.There are certainly headwinds that stem from the popularity of these STRs: as you note, more jurisdictions are changing their laws and/or requiring more from hosts.  

Let's break down a few considerations:A popular tactic is to invest in properties outside of your state, particularly if your investing objectives conflict with the state's market circumstances.

Ive been doing some research seems like guesty, hostfully, ownerez, hospitable seem to be the most popular.

Often times those competitive markets can be really hard to get a good return, I would start to look in the sub-markets/those that are less popular to find an opportunity. 

I do not know every market in the US but typically speaking popular vacation areas which drive up rates also have high real estate values.