If you're looking for uber-optimized, eldritch blast IS the best. If you're talking about most fun to play, making gishes is my specialty. Being charisma casters and having access to invocations, warlocks are already at a competitive tier OoC. Warlocks can also compete fairly competently as a DPS without needing eldritch blast. Clarify what you mean by "best", whether multiclassing is allowed, and other little tidbits. I'll update this post with my response. You're gimping yourself with no eldritch blast, so I'm going to assume no variant rulings either (Human-Variant will be the best choice in most cases simply because I love feats)
Edit 1
Pure Bladelock; Dex build
27 point point-buy
Starting Stats:
STR: 10 (+0)
DEX: 15 (+2)
CON: 13 (+1)
INT: 8 (-1)
WIS: 10 (+0)
CHA: 15 (+2)
Reasoning; Point buy caps at 15. Dex and CHA will be our main stats. You don't really want a negative modifier to anything, but something's gotta give in order for us to maximize our combat efficiency. You would be tempted to use STR as your dump stat, but you're in melee. Bad idea. You needed a pact to get magic, so let's pretend you weren't intelligent enough to become a wizard. INT is a decently dumpable stat for a warlock.
If available, I almost ALWAYS roll my stats.
Level 9Race: Dark Elf (Drow) if allowed in setting (+2 DEX +1 CHA) OR Lightfoot Halfling (+2 DEX +1 CHA)
HP: 66
STR: 10 (+0)
DEX: 17 (+3)
CON: 14 (+2)
INT: 8 (-1)
WIS: 10 (+0)
CHA: 18 (+4)
AC: 10 Base, 16 w/ Mage Armor
ASI/Feat: Resilient (+1 CON, proficient in CON save), ASI (+2 CHA); If Variant Human, (+2 DEX)
Patron:
I prefer fiend, but any of them will work. Choose your flavor.
Spells:
Cantrips; 3
Booming Blade
Green-Flame Blade
Shocking Grasp/Chill Touch (utility)
Spells; 10.
Spellslots; 2 @ 5th
Mirror Image
Hex
Armor of Agathys
Invisibility
Fireball
Shield
Absorb Elements
3 of choice
Invocations; 5 Holy hell. Not having eldritch blast AND being a pure warlock gives you some crazy at-will power
Mandatory:
Thirsting Blade
Fiendish Vigor
Mask of Many Faces (can be optional if you're only worried about combat capabilities)
Armor of Shadows
Optional:
Devil's Sight (If not DROW)
Beguiling Influence
Eyes of the Rune Keeper
Weapon: Rapier. 1d8+3, 2 attacks (thirsting Blade). 1d6 more with hex. +7 at level 11 (life drinker)
Playstyle: Be in melee, but you're not a tank. You can take some hits if you use fiendish vigor prefight (guaranteed 8 hp if you just keep casting it.) Armor of Agathys for a chunk of temp HP + Damage to attackers. Shield/absorb elements only if you think the hit is one you NEED to avoid. Use your shocking grasp to get out of melee without disengaging, and use your blade cantrips for damage. Booming blade is great if someone else in the party (bard?) can force the opponent to move willingly. Green-flame blade gives you decent multi-target damage, and the splash damage doesn't check defenses; use this to hit things you normally wouldn't waste the attack on/couldn't otherwise hit. Spells are basically up to you. You can go full utility, grab some situational AoE spells, etc.
You can make a STR variant of this build that I actually prefer, but it's aided strongly by multiclassing. I'm not a fan of full caster warlocks, but if you would like I can try to optimize a level 9 for you that is PURE caster and PURE warlock.