We regularly get asked questions like ‘what is the best Subaru engine to use in a VW conversion?’ Obviously, there is no single answer to this question, as it depends on your expectations from the conversion, and what model of VW you are converting, etc.
When first considering a conversion, it seems that quite a few people think they want a Subaru turbo engine. However, this is often based on little knowledge of what work is involved, fuel consumption, the need to uprate various other parts of their VW, etc. Usually those who really do want a turbo engine already have plans to uprate the brakes, suspension and gearbox, and have taken all this into account. A number of those who have initially asked about Subaru turbo conversions actually turn out to have never driven a VW with more than about 100 bhp, and plan to use their camper for holidays, etc. In cases like this, they are almost always going to be much happier with a naturally aspirated conversion.
To decide which engine you actually want for your conversion it is necessary to first look at what VW you are planning to convert, and what work is involved compared to all the other VW types. This is covered in the page Subaru Engine Choice Based on VW Type
Then, once you are familiar with what sort of amount of work is involved in the conversion, look at the many Subaru engine types in more detail