Williams are very good engines, not just for starting level, but for all porpose useage.
Lionel and MTH offer command control, however each company has their own system and may not work all features unless you have the same companies control system. Of course command control is more expensive per engine and the control bases are close to $300.00, give or take a few dollars depending on who sells it.
Atlas sells most of their engines with Lionel's command control system installed.
RMT also sells some lower priced engines and rolling stock, pretty good for the price; however watch out for what 'size' the RMT unit is. Sometimes the RMT is a half size unit like a Beef or a Beep engine, also pasenger sets maybe about 8 inches long per car.
There are many types of track in three rail O gauge, but stay away from custom roadbed track for now. Tubular track is best until you get more involved in the O gauge world.
Gargraves track with Ross cutom Switches is about the best you can do.
However Gargraves and Ross track have all three rails electrically seperated from each other, unlike Lionel, K-Line and Williams track which have the outside rails sharing a common electric hook-up. Also Gargraves and Ross have their own style track pins, and when used with other tubular track or other brands of track will need adapter pins. Gargraves and Ross have more switch selections and curve sizes then any other brands.
Gargraves and 027 track will match nicely with just adaptor pins being used as track pins, no heigth differance.
Atlas makes another type of three rail track and it too has its own style of track pins.
Lionel's Fastrac and MTH's Realtrax in roadbed style are two seperate systems and need adapter pins or tracks to mate to each other. Also the switches in Fastrac are super expensive.
K-Line used to make two differant types of track as well; Super Snap track, an O gauge tubular with plastic ends and darkened center rail, also Super Streets track; for use mainly with trolleys and other small vehicles.
RMT now makes the K-Line style Snaptrack. Williams by Bachmann now makes the Super Streets but is called E Z Streets.
Most engines and rolling stock should work on any track system, watch out for track sizes and large engines; SD-70mac may need a 42 inch curve or a heavyweight passenger car also.
Most transformers will work with most brands of engines, only one note here; MTH PS-2 and PS-3 will not work with Lionel's CW-80 transformer.
Lee F.