I was in KL for the last three months and one week in Penang after that. Basically I liked Penang. But I have only seen the heritage area where I stayed in a boutique hotel for 100 MYR a night (would have been 120 but I got it cheaper). I didn’t check out the newly opened co-working space (forgot the name) as I didn’t have much time and there was pretty good wifi in the hotel. I think you can save time of commuting if you stay in Penang, compared to KL. Especially if you don’t like big cities (unlike me ) it makes sense to go to Penang. Things are cheaper there (not sure about apartments), air is better, sea is closer and nicer (didn’t check out beaches though), traffic is ok (especially in the heritage area which is really quite and relaxing, as well as pretty!).
In KL I found a modern and nice apartment for 2500 MYR near the skytrain (LRT) in Petaling Jaya, about 20 min away from the main station, but not through Airbnb as they are usually more expensive on there. I found an agent which was willing to find an apartment for me. Normally they don’t do below 6 months, but she negotiated with the owner and got it for 2,5! If you want her contact, let me know. A few pics on my German language blog post here: https://www.addor.ch/phil/kl-living/