It’s Indonesia. Without a doubt any massage in Denpasar, erotic or not, will be amazing. I mean: Bali is literally on every massage stock photo. Balinese massage can be a lovely experience, even when it doesn’t “end happily”. It’s more of a spiritual thing.
Jalan Legian, the main street in Kuta is where you’ll find the best deals for foreigners. You can buy an hour of steaming hot massage for $10. Tip another tenner and you’ll get yourself a happy ending. Karma Massage (http://karmamassagebali.com/) and King of Pleasure (https://pleasurebalimassage.com/) are examples of sensual massage studios doing only outcalls.
There are also rubs and tugs in Denpasar, but they are not always foreigner-friendly and mostly operate on a “by locals for locals” basis. Safe bets in Denpasar are the Sriya Spa (https://www.facebook.com/SRIYA-SPA-BALI-917912551599535/) at Jalan Mertasari No.90 and Refrezz (https://refrezzspabali.com/) at Jl. Tukad Batanghari VI B No.6.
Keep also an eye out on soapy massage parlors. They’re supercharged studios that usually have full service on offer. Packages cost $50 at the most and that includes a hand job. The rest is to be negotiated separately. And last but not least: there is the rather famous Riverview (http://www.riverviewspabali.com/) at Jalan Kresna No.04 in Kuta.