Have to give a shout out to a Bulls Brose option. They were the first manufacturers I saw integrate the battery into the frame really well, and they’ve continued to improve upon that design. As I mentioned above, I love the wave frame. Super easy to get on and off and it’s got a cool look as well. If you’re not a fan, this bike does come in both a Diamond and step-thru frame.
Using an electric bike for long-distance touring has its pros and cons. The motor will help carry the extra weight of your kit, particularly on the hills, but you have the added hassle of having to charge the battery every night. You’ll want a powerful motor and a good battery, though if you’re fully loaded, don’t expect to achieve the maximum advertised range.
Riese & Muller’s Nevo line definitely tops my list for commuting electric bikes. These bikes are premium, custom made bikes for a reasonable, middle-of-the-road price. All Riese & Muller bikes are hand made in Germany exactly to your specifications. The Nevo line specifically is incredibly well balanced and keeps riders in a comfortable, upright position. Riders also get a suspension seatpost (either the Cane Creek Thudbuster or Satori Elegance LT), which is a nice compromise between the full suspension Homage line and a complete hardtail.
E-bikes mostly use motors and battery options from a few major suppliers: Bosch, Yamaha, Shimano, and Brose. A few other brands exist, but are less reliable or powerful. Some, like the Yamaha system, have more torque and others are quieter. But generally all four make good options. Look for motor output (in watts) which will give you an idea of total power. But watt hours (Wh) is perhaps a better figure to use—it takes into account battery output and life to give a truer reflection of power.