Piper

Stats based on FAA registry:

In Production Models

Piper PA-28 Cherokee: 2-seat or 4-seat.
Piper PA-44 Seminole: twin-engined, primarily used for multi-engined flight training.
Piper PA-46 Malibu, now called Piper M-Class: 6-seat, single engine, pressurized.

Piper PA-28 Cherokee

In production models:

Archer TX: for training, Lycoming engine.
Archer DX: for training, Continental engine (D for Diesel), burning the more efficient jet fuel.
Archer LX: for private, Lycoming engine.
Archer DLX: for private, Continental engine.
Arrow: for training, retractable landing gear.
Pilot i100: introduced in 2019, as low cost VFR and IFR trainers. IFR version includes GFC500 autopilot.

Discontinued models:

Piper PA-28-236 Dakota: a follow-on model to the Cherokee 235, was intended as a head-to-head competitor with the Cessna Skylane (the same horsepower, roughly the same interior dimensions, comparable performance, but with a low wing).
Piper PA-28-151 Warrior
Piper PA-28-161 Warrior II
PA-32 and PA-32R (with retractable landing gear), and as the name Cherokee Six suggests, it is developed from the 4-seat PA-28 Cherokee, but seats 6.

Warrior vs Archer

The Warrior is a lighter aircraft that burns less fuel as a 160-horsepower Lycoming O-320 engine powers it. However, the Archer has an improved climb rate as it has an extra 20 horsepower. Additionally, the Archer is about five knots faster than the Warrior because of its added power.

Archer II vs III

They are essentially the same plane, same engine, etc. The only real diff is the wheel pants and the front cowl. (II: 1976-1994, III: 1995-2010)

Piper PA-46 Malibu / M-Class

M350: 350 hp
M500: 500 hp
M600: 600 hp, introduced in 2015, upgraded from M500.

M350 is using a piston engine (Lycoming TIO-540), while M500 and M600 are using a turboprop engine (PW PT6A-42A).

The PA-46 was the third single-engined piston aircraft with a pressurized cabin to reach the market, after the Mooney M22 and Cessna P210 Centurion, and is the only one still in production.

Twins

All models discontinued.

Piper PA-31 Navajo: twin-engined, 5 to 7 passengers
- Piper PA-31T Cheyenne: Turboprop
- Piper PA-31-350 Navajo Chieftain
Piper PA-34 Seneca: twin-engined; basically a twin Cherokee Six.
Piper PA-42 Cheyenne: turboprop, developed from Piper PA-31T Cheyenne.

Cub

J-3 Cub and PA-18 Super Cub were so popular, thousands are still flying.