I doubt that's worth the upgrade.  Merchants is about all you have to do sometimes.

Not going to sort old school/new school as some I played in the Amiga days but carried on through the series to Windows - listing top 10 with no order

Total War series (especially the third age mod in medieval II)

LoTRO (the only MMORPG that kept my interest long enough - you can only,kill,loot,level up for so long before your brain dies)

Civ series

Dune series (Dune 2 and Emperor:Battle for Dune, the latter being the pinnacle of the RTS genre IMO)

Age of Wonders series

Gal Civ series

Elder Scrolls (3 onwards)

Warlords series

Battle Isle series (especially the futuristic battle Isle 92)

The Settlers (first one only - the rest were pants)

Good old games (chronological order):

- Defender of the crown

- War of the lance

- Panzer general (Still play it!)

- X-com

- Steel panthers

Modern favorites (favorite order)

1) Paradox games (CK2/EU3/VIC2 grouped because they would flood the list)

2) Mount&Blade

3) Civilization 5

4) World of Tanks

5) Blood bowl

Going to break it down like this:

1. Homeworld
2. Cataclysm
3. Homeworld 2
4. Sins of a Solar Empire
5. Battlefield (series)
6. Stonghold (series)
7. Everquest I
8. Fallout 2
9. World of Tanks
10. R.U.S.E.

Legacy (You're too young to remember):

1. OG C&C
2. Ascendency

Classic:

X-Com: U.F.O. Defense

Arcanum : Of Steamworks and Magick Obscura

Master of Orion 2

Master of Magic

Fallout 2

Modern:

Elder Scrolls 3 : Morrowind

Galactic Civilizations 2

Neverwinter Nights

Warhammer 40k Dawn of War series

Magic the Gathering : Tactics

Old:

Dreamweb

Neuromancer

Shadow of the Beast

Black Crypt

Moonstone 

New:

Silent Hill series to 4 including (2 was best)

Dominions 3

Thief 2

Mount and Blade multiplayer

Soul Reaver series

Pending - Dishonored, did not finish yet, likely candidate

Hm.. it's always tough

1. System Shock 1

2. Ufo Enemy Unknown (X-com Ufo Defense, in USA)

3. Thief 1

4. Betrayal at Krondor

5.  Company of Heroes

"Vintage" (PC)

Baldur's Gate Series

Neverwinter Nights Series

X Wing/Tie Fighter

Wasteland

Civ I & II (Honorable mention - face it the older ones were awesome at the time they were released.)

MoO I & II

"Vintage" (Console)

Chrono Trigger

Final Fantasy (I & II as it was sold to Americans )

Zelda, Zelda II (both NES),  and Zelda for SNES

Uncharted Waters (NES),  Uncharted Waters II (SNES)

Wild Arms (PS1)

"Modern" (PC)

Fallout 3/ NV 

Morrowind/Oblivion/ Skyrim

Mass Effect I - III

Gal Civ 2

Civ 4

FF 10  (Let's face it I played them all.  But choose the one you like best of all )

I don't like how all RPGs went to action instead of some turn based thing.  Most action systems penalize the user by agressive monsters always getting their hits in and the user penalized by not blocking or defending at the correct time.  Even worse some monster not vulnerable unless you do the right thing at the right time.  I have always been critical, but I can't change the way a whole industry went.

@Shogun: Don't forget FF Tactics.

oh no i am spending too much on crystal saga now days

Old days:

JumpMan! 

Ultima III (without a manual, and death was permanent)

Castle Wolfenstein (2D, with my friend doing the shooting, while I did the moving)

Empire

Carriers at War

Now:

HPS Panzer Campaigns

Europa Universalis 3

Skyrim

Civilization IV  (V isn't too bad, but I played IV much more)

Everquest 2  (I don't play it anymore, but like above, I played it lots while I could)

Also Centurion Defender of Rome was an epic game at the time, never owned it myself, was so jealous of my mate that had a pc with it on.