I use the powdered 'bio' versions of UK Persil and Ariel and would recommend both.
I conducted a stain removal test with both and they did very well, Persil edging out Ariel. UK Persil was third in stain removal after Quixtar's SA8 and the
German (made by Henckel) version of Persil. UK Ariel came in 4th, barely edging out Tide With Bleach (powdered version), which came in 5th, but still did an admirable job of removing some very tough stains.
Note: When I posted those test results, several AW members from the UK were surprised; their experience showed Ariel to be the better stain remover. Still others sided with Persil and my results. They are both top-notch detergents.
UK Persil also rinses out very well, even in very soft water. That's the main reason I keep some on hand. I like to use it on loads of bath towels, which tend to hold on to detergents in soft water.
UK Ariel has a bright, citrusy scent which I really like, but it doesn't rinse out as well as Persil, in my experience. Even when using a front-loader (which tends to be more airtight than most top-loaders, you can expect to smell Ariel in the areas adjacent to your laundry room. If you like the scent (and I do) that's a bonus; if you don't care for it, it's going to bother you.
I order from the Brit Superstore and have had no problems. By all means, expect shipping to be more than the cost of the actual product.
Let us know what you think of the products, should you decide to place an order.