The Infinity models are metal and have won TTGN's sci-fi mini of the year the last 4 or 5 years running, IIRC.
They're beautiful - if you're into painting and like their aesthetic then I'd strongly recommend them. There is no higher quality mini range out there, IMO.
Gamers' World on Jervis street stock them, so if you did decide to risk a journey into town you can check them out there.
Another possibility is Malifaux. They're fantasy/steam-punk and Wyrd Miniatures used to be a company producing minis for painters that then created a game - Malifaux. I think the Infinity minis are nicer but the Malifaux ones are some of the best fantasy minis out there. They're also metal. I don't find them particularly difficult to paint - they have so much fine detail that they take washes and thinned paint very well. Some of them are a PITA to assemble though - they're more realistically proportioned than heroic 28mm like 40K/WHFB so arms and legs can be thin.
I hear that Sedition Wars minis by Studio McVery -
http://www.seditionwars.com/ are very nice. I've not seen them myself though.
Check out
http://www.pig-iron-productions.com/ for 28mm sci-fi squad level stuff too. I like the minis - not as fantastic as Infinity but they're much cheaper. I have their Kolony rebels and militia.
As for other paints being as good as GW's - typically they're better than GW's IMO.
Vallejo in particular are the ones most commonly used by professional miniature painters. My mini-painting man-crush Angel Giraldez seems to use them exclusively -
http://studiogiraldez.blogspot.ie/ - he's the official Infinity painter. Many other professionals use them too. BTW check out his blog for some beautiful Infinity & Anima tactics minis. He even lists the paints he used on a particular mini and will answer questions on them or technique in his comment section.
Privateer Press's line is imo excellent, except for some of their metallics.
I don't know Army Painter bottle paints but I'm sure they're fine and you can find reviews of them online. I use their coloured primer sprays - mostly just white but I also have their brown and pink for the odd purpose.
GW paints historically have been mediocre at best IMO although they did a re-working of their entire paint line recently. From what I've seen so far, I still prefer PP and Vallejo.
I have a mix of paints from all the lines as they're all good enough but I do try to get PP or Vallejo where I can as I know them and think they're excellent.